1. Field of the Invention
This invention relates to silicon nitride-containing beads and aggregates thereof.
2. Description of the Related Art
High density silicon nitride ceramics (i.e., silicon nitride ceramics having a bulk density approaching or equal to theoretical density) having good oxidation resistance, mechanical properties, and thermal shock resistance are known. Such ceramics are used, for example, as cutting tools and as components for automotive engines and gas turbines. Densification techniques for providing the high density silicon nitride ceramics include pressureless sintering, gas pressure sintering, hot pressing, and hot isostatic pressing. Furthermore, sintering aids such as rare earth oxides, magnesia, and alumina are often used to assist densification.